Saturday was the third time Rhea was able to raise enough money - $9,200 this year - to cover transport costs to bring the truck to Ambler.
It started 11 years ago, at her fifth birthday party. She received an abundance of gifts. Even then, it seemed unfair.
"From a very young age, I was sad that other kids weren't so lucky," she said.
She told her parents that when she turned 6, she wanted a party where guests would bring cash instead of gifts and wash cars to raise money for kids who weren't lucky.
At age 6, she didn't forget. Rhea had her first car-wash party. Her parents put her in touch with Feed the Children, beginning an annual tradition that will continue in June with a car wash for Rhea's 17th birthday on April 24.
Her goal? $10,000.
Rhea wants to be a lawyer. "I'm very passionate about justice," she said. "There's too much injustice in the world."
Mark Opgrande, a spokesman for Feed the Children, said Rhea was "kind of unusual for being so young and stepping up to serve the community."
As a charity, Feed the Children has had its critics, who have complained that overhead and management took too much of the money. But a new CEO has promised changes.
Last year, Feed the Children opened a warehouse in Bethlehem, Pa. - food for Saturday's event was transported from there.
Rhea said she had become very aware of poverty through her car-wash charity.
"Need is everywhere," she said. "I know some of these boxes are going to kids in my school."
To qualify for help at the cupboard, a family of four must live in or near Ambler and earn less than $679 a week, although director Christine Bouley said she was flexible depending on circumstances.
Some receiving boxes Saturday had jobs but didn't earn enough. One was a caseworker who helps others get food stamps. Another was a home health worker earning $11 an hour.
One man went from doing OK to struggling, as Rhea said; he lost his job in October 2012. Separated from his wife, he's down to one meal a day.
When his kids visit, they, at least, also get breakfast.
"It's hard," he said, too embarrassed to have his name in the paper. "You sell what you can. You can survive on a lot less than you thought."